21012140 has 24 divisors (see below), whose sum is σ = 44584512. Its totient is φ = 8317440.

The previous prime is 21012137. The next prime is 21012151. The reversal of 21012140 is 4121012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3476 + ... + 7355.

It is an arithmetic number, because the mean of its divisors is an integer number (1857688).

Almost surely, 2^21012140 is an apocalyptic number.

21012140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012140 is an abundant number, since it is smaller than the sum of its proper divisors (23572372).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21012140 is a wasteful number, since it uses less digits than its factorization.

21012140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10937 (or 10935 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21012140 is about 4583.9000861712. The cubic root of 21012140 is about 275.9455714277.

Adding to 21012140 its reverse (4121012), we get a palindrome (25133152).

The spelling of 21012140 in words is "twenty-one million, twelve thousand, one hundred forty".